Removing and resealing a leaking portlight
Things you will need
Silicone adhesive sealant, new rubber gasket, acetone, masking tape, assorted screwdrivers, flat blade, locking pliers.
Dismantling the portlight
1
Peel away the inner rubber seal, if there is one. The window pane is usually held in place by inner and outer frames, which are either bolted or screwed together, normally from the inside. Some have a gasket between the frame and the glass, which will need to be replaced if it shows any sign of deterioration.
2
Take care when removing the fastenings as these will need to be reused – ordering replacements can prove tricky and time-consuming. It is best to use a regular screwdriver as power tools can easily strip the heads. If some of the fastenings are hard to remove, leave them and remove those that will undo first.
3
With the fastenings removed, lift off the inside frame. This will most likely need a good clean.
4
Remove the outside frame. Start by pushing gently on the pane from the inside and see if the frame moves, mindful that it will also be sealed from the outside. Then on the outside, use a flat blade between the frame and the hull to gently prise the window free. 5
With the inner and outer frames and pane removed, thoroughly clean around the opening, removing all the old sealant – acetone normally works well. Use a scraper if needed, taking care not to scratch the hull or superstructure. 6
Check the condition of the edges around the opening. If there are any signs of rot in the exposed core, this needs to be scraped out to a depth beyond the bolt holes. Make sure this is cleaned out as well as possible and left to dry. The resulting cavity can then be filled with epoxy and left to harden.
7
The frame is normally in two halves held together by a fixing plate. This needs to be unscrewed. The frame can then be gently prised apart and the window pane removed, peeling away the old rubber gasket. Keep the old gasket as a template for ordering a new one. 8
Thoroughly clean the frame and window pane of any residue left by the old seal. Check if the old gasket was bedded in by silicone, as this is often the case with aluminium windows.
REPAIRING A LEAKING HULL-DECK JOINT
If you suspect a hull-deck joint has failed, then being absolutely sure where the actual leak is occurring is of prime importance. Areas to check are near the deck fittings, where the decks may be put under considerable stress by the rigging and the continued flexing of the hull.
Another area to check is where mooring cleats have been subjected to excessive strain or when a boat has been left tied alongside with insufficient fenders in place.
Hull-deck joints are designed not to come apart, so they are permanently bonded, often covered up and some are even glassed in. This can make repairing them very challenging.
■ Getting access
Hull-deck joints are usually fastened with bolts from above and nuts below. Others are fastened by screws and others by rivets. Getting access to the underside of the fastenings usually entails stripping away the headlinings or panels. So the first thing to do is check what type of fastenings you have on your boat and then work out how you are going to get access to them and remove them.
■ Loosen the rigging
Before you begin to unfasten things, it is a good idea to slacken off the rigging to ease the tension acting along the length of the joint.
■ Removing the rail
Back on the outside, it’s common for the joint to be protected by a rubber fender or toe rail, which may be constructed either from aluminium or wood. The rail invariably needs to be removed first. Metal rails might be bolted, screwed or riveted. Wooden rails will be bolted or screwed.
■ Inspection
With the toe rail removed, closely examine the joint and get a better idea of where the problem lies. It might be there are only a few places where leaks are occurring, meaning that a localised repair is all that is required. A thorough inspection at this stage will help you decide.
■ Unfasten the joint
Remove the fasteners holding the joint in place around where the problem lies. The reason for this is that you need to open up the joint in order to apply new sealant for the repair. Alternatively, you may choose to rebond the entire length.
■ Remove the old bedding compound Before new sealant can be added, all the old bedding compound must be removed, using a reefing iron or similar to scrape out the old material. Use wedges to separate out the joint flanges enough to get access for the repair.
■ Fill the joint with new sealant
With the old joint cleaned out as well as possible, fill the joint with polyurethane sealant, ensuring there is sufficient to reach well into the joint beyond the fastening holes.
Once the sealant has been applied, remove any wedges and, where possible, clamp the joint to ensure there will be a good seal along its length.
■ Refasten the flange
Refasten the flange with through-bolt fittings if possible, but if not, use self-tapping stainless steel screws.
Apply extra sealant beneath the heads of the bolts or screws, but leave the fastening nuts beneath clear of sealant to make it easier for the joint to be undone in the future. Then clean up any excess sealant before it cures.
■ Refasten the rail
Refasten the toe rail, bedding it with polyurethane sealant and bolts or screws as appropriate. Reattach the fender strip if there is one.
STRESS CRACKS
It’s quite common to find cracks in the gel coat when inspecting the deck and superstructure of a GRP boat. A trained eye will be able to inspect these and know whether they are purely cosmetic or of structural concern.
It’s important to differentiate between a crack and a scratch.
Scratches in a gel coat may be unsightly, but these are blemishes on the surface only.
Cracks, on the other hand, go right through the gel coat and are an indicator that there has been some level of structural failure beneath.
How do you tell the difference if the answer is not obvious? See the table (below) for some advice.
Causes
The main causes of gel coat crazing are stress and movement. Gel coat is hard and brittle while by comparison the glassfibre laminate beneath is softer and more flexible. So if the laminate bends or moves, the gel coat won’t bend with it and cracks as it is brittle.
There are two main types of stress crack: linear cracks and star cracks. Linear cracks tend to run in parallel lines and star cracks spread out in a starburst-type pattern. The patterns of cracks are a clue to what caused them:
■ Star cracks: Star cracks are caused by external impact, with the central area of the crack being the point of impact and concentric circles spreading outwards, like a spider’s web.
They are also caused by flexing around a point, for example around a stanchion base that has been leant on or pulled heavily by crew members getting aboard.
■ Linear cracks: Linear cracks indicate damage caused by bending or flexing. These occur, for example, along deck edges, where the deck meets the cabin sides, where the moulding curves upwards away from the cockpit area to the deck or around the edges of cockpit lockers.
Repairs
The underlying cause of stress cracks needs to be identified before a repair is carried out, because if there is a structural problem beneath the deck this will need to be repaired first.
This may be a question of fitting backing plates or stiffening an area with additional glassfibre laminates. Check the integrity of the laminate immediately beneath the affected area and see if it is watertight.
Thankfully, most deck stress cracks can be repaired fairly easily, providing the underlying laminate is intact. Here are the steps involved:
■ Remove any deck hardware necessary to gain access to the whole length of the crack (or cracks).
■ Grind out the cracks using a small, high-speed rotary tool. An alternative is to
use the corner of a good-quality scraper to open the cracks up, chamfering both edges in the process.
■ Clean the cracks and repair the area with acetone.
■ Mask the repair area off prior to filling. This will prevent the surrounding gel coat and fittings from being damaged when sanding the repair.
■ Decide whether you need to tint the filler to match your gel coat, using gel coat pigments. This will require some practice to get a good result/
■ Fill the exposed cracks with gel coat filler using a plastic spreader, making sure the cracks are completely filled.
■ Leave the filler to harden off. When fully cured, sand the filler with 240-grit wet and dry paper, used wet.
■ Check the filler repair is flush and refill if necessary. Then rub back and smooth off with a finer 600-grit wet and dry paper. ■ When the gel coat surface is flush, remove the masking tape and apply rubbing compound to give a gloss finish to the repair, which can then be polished with a wax polish.
VOIDS
When fibreglass decks are being laid up, pockets of air can get trapped in sharp bends and corners of the moulding, also known as radiuses. This happens because the lay-up mat or cloth does not completely fill these corners. The gel coat beneath will have done so, being a lot more fluid during the construction stage and the result is a weak spot with a void beneath. When pressure is applied from above, the gel coat will crack like an eggshell, exposing the void beneath.
Repairing a small void is a similar process to repairing a stress crack, but a larger void will require filling the cavity with polyester resin, followed by gel coat filler. Here are the steps involved:
■ Chip out the void, removing all the cracked gel coat. This can be done with a rotary tool, angled scraper or similar. Chamfer the edges of the gel coat around the void.
■ Clean the area and exposed void with acetone.
■ If the void is large, fill it with polyester resin mixed with chopped strand mat (CSM). This will bond well to the laminate beneath. Leave enough depth for the gel coat filler to be applied at the surface.
■ When the polyester resin has hardened, fill with the gel coat filler.
■ When the gel coat filler has hardened, sand the filler with 240-grit wet and dry paper, used wet. Check the filler repair is flush and refill if necessary. Rub back and smooth off with finer 600-grit wet and dry paper.
■ When the gel coat surface is flush, apply rubbing compound to give a gloss finish to the repair, which can then be polished with a wax polish.